The term Ecclesiastical Latin (sometimes called Church Latin) means the Latin language that is used in documents of the Roman Catholic Church and in its Latin liturgies. It is not a distinct language or dialect, but only the Latin language used for ecclesiastical purposes, because the same language can be used also for commercial or other purposes.

The Church issued the dogmatic definitions of the first seven General Councils in Greek, and even in Rome Greek remained at first the language of the liturgy and the language in which the first Popes wrote. The Holy See is not obliged to use Latin as its official language and, in theory, could change its practice.

But Latin has the advantage that the meaning of its words have less likelihood of changing radically from century to century. This helps to ensure theological precision and orthodoxy. Accordingly, recent Popes have reaffirmed the importance of Latin for the Church and in particular for those undertaking ecclesiastical studies.

A Primer of Ecclesiastical Latin by John F. Collins, (Catholic University of America Press, 1985) ISBN0-8132-0667-7. A learner's first textbook, comparable in style, layout, and coverage to Wheelock's Latin, but with text selections from the liturgy and the Vulgate. It also contains translation and composition exercises.